bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Ground Shear Strain (GSS) In Mapping, Liquefaction Vulnerability Potential Using HVSR (Horizontal To Vertical Spectral Ratio) Method. Case Study: Sepaku Subdistrict, North Penajam Paser Regency, East Kalimantan
Authors: Kusuma Wira Hadi , Sanny T.A. 
Published: May 2022

Abstract
East Kalimantan has been designated as the new Capital Province of Indonesia. The criteria for determining the relocation of the nation's capital have passed various studies in the placement of a new state capital, one of which is by reviewing disaster aspects such as the risk of earthquakes, volcanoes and tsunamis. Based on historical records of earthquakes that have occurred, East Kalimantan is not a completely safe area from potential earthquakes or tsunamis. By using the HVSR method, the authors tried to determine the value of Ground Shear Strain (GSS) in the research area, namely Sepaku District, Penajam Paser Utara Regency. The result show that there were three zones namely Zona A, Zone B and Zone C had GSS values in Sepaku Subdistrict with landslides, soil compaction and liquefaction potential, namely 0.4 - 0.54. The result of HVSR interpretation curve are based on the phenomenon of the resulting ground shear strain value in accordance with the geological conditions in the research area of the Sepaku Subdistrict, Penajam Paser Utara Regency, East Kalimantan in characterizing the soil profile in the study area.
Superplastic behaviour of AA5083 sheets in the presence of an oscillating load
Authors: Dastgiri M S , Fuerth Z , Kiawi L , Ryzer E , Green D E 
Published: May 2022

Abstract
The superplastic flow behaviour of AA5083 sheets was investigated at 450°C in the presence of a minor oscillating load. Uniaxial tensile specimens were tested to fracture at constant strain rates with a minor oscillating load superimposed onto the monotonically increasing tensile load. In each test, the oscillating load was applied as a sine wave having a constant amplitude of 0.5 N and a constant frequency. A series of tests was conducted in which the strain rate ranged from 0.001 to 0.4 s-1 and the frequency of the oscillating load ranged from 10 to 40 Hz. And other tensile specimens were subject to a constant mean load with a superimposed oscillating load until a predetermined elongation was reached. The flow behaviour of AA5083 showed a significant sensitivity to the oscillations although the tensile strengths remained practically unchanged. The addition of a minor oscillating load resulted in a 20% - 50% relative increase in fracture strain for the strain rates considered compared to the same tensile tests without oscillation. Finite element simulation of the tensile tests conducted at constant mean load with superimposed oscillations were carried out with LS-Dyna using material data obtained from the experiments. The numerical simulation results were compared with experimental results obtained under the same loading conditions to confirm their validity. The addition of a minor oscillating load led to greater uniformity in thickness in the specimen gauge. It can be concluded that superimposing a minor oscillating load during superplastic forming results in significantly greater deformation prior to fracture.
Warping and springback reduction in bending of U-profiles through partial heating over the cross-section
Authors: Hoffmann E. , Kolpak F. , Tekkaya A. E. 
Published: May 2022

Abstract
Bending of profiles is challenging due to the high stiffness and possible deformations in the process. Especially bending of profiles with asymmetric cross-section regarding the force initiation axis leads to unwanted warping of the bent profile. This warping results from the position difference between the force initiation axis and the shear center, implying torsion moments on the profile. To prevent profile warping the use of shape-bound tools or a change of the force initiation axis position are common practices, though these methods reduce the flexibility of the process. A new method to prevent profile warping during bending is the use of partial, cross-sectional heating. Due to thermal softening in one profile area a quasi-symmetric bending case is achieved, which changes the position of the stress-free fiber and thus reduces the torsion moment. In this work, the warping and springback behavior of partially heated U-profiles consisting of S500MC steel after a three-roll push bending process is investigated using experimental methods. Through partial heating of one profile area to up to 600°C, a warping reduction of 83 % and a springback reduction of 69 % were achieved.
Improved formability of HMGF components by preforming in an upset bulging process
Authors: Haase R , Werner M , Kräusel V , Alimov A , Sviridov A , Härtel S 
Published: May 2022

AbstractHot Metal Gas Forming (HMGF) is a well-established combination of a profile hydroforming operation and an in situ hardening process. Roof rails and camshafts are typical applications. A significant limitation of the component geometry is the strain-related material thinning. In the polar coordinate system of the tube-shaped parts, the strain can be divided into circumferential and longitudinal portions. To achieve higher expansion ratios in circumferential direction, a longitudinal compression is necessary. In a conventional, non-tempered process setup this is achieved by an axial feeding movement during the forming operation. Under tempered conditions, in particular by friction coefficients well above 0.3, this is no longer possible in a controlled process. Anyhow, a beneficial material pre-distribution is required to enlarge the circumferential strain before material failure occurs. In the proposed preforming operation, the longitudinal compression is achieved by offset bulging. Based on aspect ratios between initial diameter, wall thickness, initial length and compression stroke, a specific, controlled wave pattern is achieved on the specimen. Subsequently, the semi-finished parts undergo the HMGF process in an austenitisation, transfer, forming and quenching procedure. By means of continuous, finite element based simulation and related model calibration in experimental trials, a significant increase in geometric complexity is achieved.
A case study of mechanical and thermal fatigue of press hardening dies
Authors: Chantziara K , Javadzadeh Kalahroudi F , Bergström J , Grehk M , Ulfberg P 
Published: May 2022

Abstract
Press hardening provides ultra-high strength steel components, typically boron steels, of complex geometries. In the process, the steel sheet is heated in a furnace to the austenitization temperature, transferred to the press, then simultaneously formed at high temperature and cooled in the die. Life limiting factors for the press hardening dies are mechanical fatigue, thermal fatigue, and wear. In the present case study two die segments were selected where critical damages were mechanical and thermal fatigue, respectively. The dies were made of a H13 type premium hot-work tool steel with complex heated die technology, die design integrating an advanced cooling system, for pressing automotive frame parts.
The first die failed due to mechanical loading with a crack initiated from the ejector pin area. The die design, the mechanical loads, the elevated temperature, and the tool steel crack resistance are main factors to consider. In the second die cracks initiated from an ejector pin hole, as well, due to thermal cycles causing alternating compressive and tensile stresses at the surface, which led to crack nucleation because of the accumulation of local plastic strain in the surface.
Improvement of shear cutting process by stress superposition via cross-elastic partholder
Authors: Briesenick D , Liewald M , Senn S 
Published: May 2022

Abstract
High quality requirements for shear-cut workpieces made of advanced sheet metal materials nowadays pose highest demands on cutting technologies. In this context, stress super-position in shear zones represents a common approach to adjust cutting surface quality or reduce trim load, but usually requires sophisticated process technologies. For example, fine blanking technology allows to increase clean-cut portion, but requires advanced tool and press technology. Given this background, the present paper deals with a novel, low-cost and straightforward approach of stress superposition in conventional shear cutting processes and tools. For this purpose, the partholder was geometrically modified to achieve vertical and horizontal force transmission into the blank. Presented investigations with implemented Z-shaped partholder and its cross-elasticity show a significant impact on cutting surface quality. The results were obtained by a numerical study using the FEA-Software DEFORM 2D, wherein geometry and process parameters were varied. By superposing compressive stresses, clean-cut portion could be increased up to 43 % compared to conventional shear cutting of DP600 having a sheet thickness of 1 mm. Additionally, rollover height was significantly reduced by up to 50 % due to the transversal forces of the cross-elastic partholder, while burr height could be kept constant.
Design Guidelines for interlocked stator cores made of CoFe sheets
Authors: Martin D M , Bäcker F , Deusinger B , Kubik C , Gehringer P , Schröder J , Groche P 
Published: May 2022

Abstract
CoFe lamination stacks used for high-performance electric motors can be manufactured economically in high volumes by interlocking. In order to ensure sufficient joint strength with minimized sheet thickness, a comprehensive knowledge of the influences of various process parameters, such as embossing depth, clearance and counter punch force, is essential. To analyze these parameters, which also influence the magnetic properties, experiments are carried out and resulting joint strengths are determined in top tensile tests. The negative influences of the cutting process on magnetic conductivity and thus hysteresis losses due to residual stresses and plastic deformation are well known. In the subsequent stacking step, an influence of embossing and pre-stresses on the material properties is expected. In addition, local electrical contacts between the sheets may occur due to the interlocking process, causing additional eddy currents. Loss measurements are conducted to investigate the effect of the joining process on the magnetic properties of the stack. In doing so, the influence of process parameters such as the embossing depth and clearance on eddy current power losses is analyzed.
Evaluation of hole expansion formability of high strength AA7075 alloy under varying temper conditions
Authors: Prasad Kali , Ebrahim Abrar Salam , Krishnaswamy Hariharan , Chakkingal Uday , Banerjee Dilip K. 
Published: May 2022

Abstract
There has been a widespread increase in the use of aluminum alloys in automotive industries for meeting ever-growing light-weighting requirements. However, edge formability is a critical manufacturing challenge that restricts their widespread use. Edge formability of sheet metal is determined using a hole expansion test (HET) and is evaluated by the hole expansion ratio (HER). The present study investigates the effect of temper conditions on the edge formability of AA7075 alloy sheets. Hole expansion tests were conducted in different temper such as W-temper (super saturated solid solution followed by water quenching), under aged (UA), and peak aged (PA) conditions. Two different hole preparation techniques, a punching and a drilling process, were used to prepare samples with varying edge conditions. The results demonstrate that the W-temper has the highest edge formability irrespective of hole edge conditions. Researchers have reported that uniaxial stress state prevails at the hole edge during the HET. Consequently, uniaxial tensile tests were conducted on for each temper condition and various tensile properties such as yield stress (YS), ultimate tensile strength (UTS), ratio of yield stress to ultimate tensile strength (YS/UTS) were determined to evaluate edge formability. Furthermore, microstructural and failure analysis of the failed specimens were performed to explain the deformation behavior during the HET.
Stretch flangeability of AHSS automotive grades versus cutting tool clearance, wear, angle and radial strain gradients
Authors: Larour P , Hinterdorfer J , Wagner L , Freudenthaler J , Grünsteidl A , Kerschbaum M 
Published: May 2022

Abstract
Stretch flangeability tests are performed on cold rolled AHSS automotive steel grades for crack sensitivity evaluation. The ISO16630 tests procedure is used with different cutting edge conditions including cutting clearance, cutting tool wear, cutting tool angle and hole expansion punch tool geometry. Among all influence parameters, the cutting clearance is considered to be the most critical to control. Low (<10%) and high (>20%) clearances are significantly detrimental to hole expansion ratio (HER). An optimum in HER is reached around 15% clearance. Both cutting punch wear and cutting die wear each affect negatively the HER values in comparison to new sharp cutting tools. Varying the cutting angle with concave and convex hole punching tool geometries instead of orthogonal cutting has a rather negative effect on stretch flangeability due to irregular cut edge quality along hole perimeter and excessive tool wear in the concave configuration. The influence of hole expansion punch geometry (flat R25, biaxial Nakajima R25 vs. ISO16630 60° conical) on the HER values is also investigated. The (true) HER values are proportional to the FE simulated logarithmic radial strain gradient at fracture.
Modeling tension-compression asymmetry and failure anisotropy in bending operations of a magnesium alloy
Authors: Steglich D , Besson J 
Published: May 2022

Abstract
The deformation behavior of the magnesium sheet alloy AZ31 at room temperature is investigated using different standard and non-standard mechanical tests as well as respective finite-element simulations. In order to address the bendability, three-point bending tests were performed for different orientations of the sample with respect to the sheets axes of orthotropy. The elastic-plastic deformation was modeled using a two-yield-surface model, which is able to describe the evolving strength differential effect as well as the anisotropy of the material. For the prediction of material failure, a numerically efficient damage criterion based on transformation of strain rates is calibrated and applied. It is shown that this model is able to predict the observed edge failure of specimens with good accuracy.
Effects of heavy Si doping on the structural and optical properties of n-GaN/AlN/Si(111) heterostructures
Authors: Zambrano-Serrano M A , Hernández Carlos A , de Melo O , Behar M , Gallardo-Hernández S , Casallas-Moreno Y L , Ponce A , Hernandez-Robles A , Bahena-Uribe D , Yee-Rendón C M , López-López M 
Published: May 2022

Abstract
n-GaN/ AlN heterostructures were grown by molecular beam epitaxy on Si(111) substrates.The GaN films were n-type doped with silicon and the effect of doping concentration on the structural and optical properties was studied. Si doping promotes a reduction of dislocation density as revealed by x-ray data analysis and Transmission Electron Microscopy. Furthermore, a decrease in the yellow band measured by Photoluminescence Spectroscopy was observed when silicon doping concentration was increased up to 1.7 × 1019 atoms cm−3. A particular mosaic structure was induced by the Si-doping as inferred from Rutherford Backscattering measurements. The crystal quality shows a small degradation for very heavily doped samples (1.3 × 1020 atoms cm−3).
Optimization of dry sliding wear behavior of epoxy nanocomposites under different conditions
Authors: Namdev Anurag , Purohit Rajesh , Telang Amit , Kumar Ashish , Saxena Kuldeep K , Mabuwa Sipokazi , Msomi Velaphi , Mohammed Kahtan A 
Published: May 2022

Abstract
This paper evaluates the wear properties of epoxy nanocomposites containing GNP (Graphene Nanoplatelets). In this research, variation of GNP (0,0.1, 0.25, and 0.5 wt%) were used to make nanocomposites. The hand layup technique was used for the fabrication of different composites. The Taguchi method is used to optimize the wear test and its related characteristics. Analysis of variance is used to understand the correlation between input variables and response measurements. Load (0.5, 1.0, 1.5, and 2.0 kg) and time (4, 6, 8, and 10 min) are the main variables for exploring wear characteristics for this study. It has been discovered that minimum wear in terms of mass loss and friction coefficient are minimum at 0.5 wt% GNP. Scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDX), and RAMAN spectroscopy were used to characterize the wear mechanism. The result shows that the optimized value is closer to the experimental value.
Predictions of stress distribution and material flow in coining process for bi-material commemorative coin
Authors: Peng Yuchun , Xu Jiangping , Wang Yuan 
Published: May 2022

Abstract
Bi-material commemorative coins have the characteristics of weight reduction, beauty and corrosion resistance. However, due to different characteristics of bi-materials, defects such as stress concentration, drop of inner core and micro-cracks often occur at interface of materials in usage. Engineers usually employ multiple mold trials to check the bonding state of two material regions, judge the stress concentration area and modify the process to avoid micro-crack sprout. Based on the professional metal forming software Deform 3D, stress distribution and material flow in coining processes for single and bi- material commemorative coins are studied. Numerical examples demonstrate that there are three typical stages over the whole process whether the coin is single or bi- material. And stress concentrations appear at the corners of upper/lower dies and the material interface in case of bi-material. The former concentration lead to sprout of micro-cracks along the shear bands and the latter triggers cracks at the interface. In addition, two materials with different hardness are adopted in the core and ring, respectively, to investigate the mutual interaction behavior at interface. Numerical findings indicate that large strains occur at the edge and the interface in case of bi-material with soft core. These imply that deep adhesion happens at the interface in case of that soft material is in the core. It suggests that hard material in the inner core and soft one in the outer ring may cause falling of the core.
Exploration of the atomic-level structures of the icosahedral clusters in Cu–Zr–Al ternary metallic glasses via first-principles theory
Authors: Lu Wenfei , Wang Zhilue , Xiang Hongping , Feng Aihan , Shen Jun 
Published: May 2022

Abstract
The atomic-level structures of the icosahedral clusters in Cu–Zr–Al ternary metallic glasses were studied via the first-principles theory. The rules of icosahedra stability were determined. Icosahedra with a better chemical order or with a better symmetry exhibited a better stability. The strong connectivity between Al atom and Cu and Zr atoms was observed as demonstrated by the obvious degree of ‘bond shortening’. The Al atom contributed more to the structural stability when used as the central atom than the other atoms. Therefore, the addition of even a small amount of Al atom to the Cu–Zr binary system remarkably improved the stability of the icosahedron structures. The continued addition of Al atoms had a lower contribution to the improvement to the glass-forming ability of the Cu–Zr–Al alloys.
CATHAI: cluster analysis tool for healthcare-associated infections
Authors: Cuddihy Thom , Harris Patrick N A , Permana Budi , Beatson Scott A , Forde Brian M 
Published: May 2022

Abstract

Motivation
Whole genome sequencing (WGS) is revolutionizing disease surveillance where it facilitates high-resolution clustering of related organism and outbreak detection. However, visualizing and efficiently communicating genomic data back to clinical staff is crucial for the successful deployment of a targeted infection control response.

Results
CATHAI (cluster analysis tool for healthcare-associated infections) is an interactive web-based visualization platform that couples WGS informed clustering with associated metadata, thereby converting sequencing data into informative and accessible clinical information for the management of healthcare-associated infections (HAI) and nosocomial outbreaks.

Availability and implementation
All code associated with this application are free available from https://github.com/FordeGenomics/cathai. A demonstration version of CATHAI is available online at https://cathai.fordelab.com.
Preoperative prophylactic active vitamin D to streamline total thyroidectomy
Authors: Annebäck Matilda , McHale Sjödin Edward , Hellman Per , Stålberg Peter , Norlén Olov 
Published: May 2022

Abstract

Background
Hypocalcaemia is a common complication after total thyroidectomy (TT). Treatment consists of calcium and active vitamin D supplementation. Low levels of vitamin D before surgery have been shown to be a risk factor for postoperative hypocalcaemia, yet studies examining routine preoperative vitamin D supplementation have shown conflicting results. This retrospective cohort study aims to investigate the potential benefit of preoperative active vitamin D supplementation on hypocalcaemia and its symptoms after TT.

Methods
This study included patients undergoing TT at Uppsala University Hospital from January 2013 to December 2020, resulting in a total of 401 patients after exclusion. Routine preoperative alfacalcidol treatment was initiated for all TT patients in January 2017 resulting in two groups for comparison: one group (pre-January 2017) that was prescribed preoperative alfacalcidol and one that was not. Propensity score matching was used to reduce bias. The primary outcome was early postoperative hypocalcaemia (serum calcium, S-Ca less than 2.10 mmol/l); secondary outcomes were symptoms of hypocalcaemia and length of stay.

Results
After propensity score matching, there were 108 patients in each group. There were 2 cases with postoperative day one S-Ca less than 2.10 in the treated group and 10 cases in the non-treated group (P &lt; 0.001). No patients in the treated group had a S-Ca below 2.00 mmol/l. Preoperative alfacalcidol was associated with higher mean serum calcium level day one (2.33 versus 2.27, P = 0.022), and reduced duration of hospital stay (P &lt; 0.001). There was also a trend toward fewer symptoms of hypocalcaemia (18.9 per cent versus 30.5 per cent, P = 0.099).

Conclusions
Prophylactic preoperative alfacalcidol was associated with reduced biochemical hypocalcaemia and duration of hospital stay following TT. Also, with this protocol, it is suggested that routine day 1 postoperative S-Ca measurement is not required.