bluuebunny/crossref_metadata_2025 huggingface dataset:
Piezo2 integrates mechanical and thermal cues in vertebrate mechanoreceptors
Authors: Zheng Wang , Nikolaev Yury A. , Gracheva Elena O. , Bagriantsev Sviatoslav N.
Published: August 2019

Tactile information is detected by thermoreceptors and mechanoreceptors in the skin and integrated by the central nervous system to produce the perception of somatosensation. Here we investigate the mechanism by which thermal and mechanical stimuli begin to interact and report that it is achieved by the mechanotransduction apparatus in cutaneous mechanoreceptors. We show that moderate cold potentiates the conversion of mechanical force into excitatory current in all types of mechanoreceptors from mice and tactile-specialist birds. This effect is observed at the level of mechanosensitive Piezo2 channels and can be replicated in heterologous systems using Piezo2 orthologs from different species. The cold sensitivity of Piezo2 is dependent on its blade domains, which render the channel resistant to cold-induced perturbations of the physical properties of the plasma membrane and give rise to a different mechanism of mechanical activation than that of Piezo1. Our data reveal that Piezo2 is an evolutionarily conserved mediator of thermal–tactile integration in cutaneous mechanoreceptors.
Texture effect on fatigue crack propagation in aluminium alloys: An overview
Authors: Zhao Qi , Liu Zhiyi , Hu Yangcheng , Li Fudong , Luo Cheng , Li Shasha
Published: August 2019

Texture or grain orientation was of crucial importance to fatigue crack propagation (FCP) in aluminium alloys due to boundary character between neighbouring grains and crack closure effect. The current understanding of the relationship among texture, grain size, slipping and crack propagation at fatigue stage I to III was reviewed and discussed. The recommendations for improving FCP resistance were proposed. Intensifying Goss, P and Q textures and moderating these grains were an effective method to improve FCP resistance in Paris regime. However, in stage I, due to the predominated crack closure effect, large grain is beneficial for improving the threshold value of crack propagation. Principally, excellent FCP resistance could be obtained at a balance of crack deflection and crack closure.
When metaphors become cognitive locks: occupational pension reform in Norway
Authors: Hagelund Anniken , Grødem Anne Skevik
Published: August 2019

The reform of the Norwegian pension system in the early 2000s sparked off a need to reform occupational pensions. In the private sector, this was done in negotiations in 2008. In the public sector, a similar attempt in 2009 failed, and the process was only finalized in 2018. We aim to show how discourse, and the way the issues were framed through narratives and metaphors, affected the reform processes in 2008/2009. We outline the significance of different constellation of actors in the two sectors, and show how this affected the ability to achieve common understandings (coordinative discourse) and popular support (communicative discourse). We then focus in particular on one popular metaphor, namely the toiler, and show how toilers emerged in different guises in both the private and public sector negotiations. A clear notion of what the toiler needed was constructed during the private-sector negotiations. When negotiations moved to the public sector, and a different type of toiler entered the picture, key reform architects were unable to adjust. The metaphor of the toiler ended up as a ‘cognitive lock’ that hampered rather than promoted reform in the public sector.
Career motives according to degree of religiosity among Jewish students in Israel
Authors: Sharabi Moshe , Polin Brian A
Published: August 2019

Members of Israel’s Jewish population self-identify along religious lines as ultra-orthodox, religious, traditional, or secular. Adherents of each group maintain different lifestyles and different social, political and economic values. This unique study attempts to reveal the
differing intra-state career motives among these sub-groups. The global research project GUESSS (Global University Entrepreneurial Students‘ Spirit Survey) included 995 Israeli students, who were asked about their career motives. The findings reveal that there is a very high similarity
between ultra-orthodox and religious on one hand and between traditional and secular on the other hand, regarding career motives. Ultra-orthodox and religious had a significantly lower motive for autonomy and control, for a stimulating job and for realizing dreams and creativity than traditional
and secular. Gender and age do not affect the motives, while military service and family status have a significant effect on the motive for autonomy and control.
Differences in visceral adipose tissue and biochemical cardiometabolic risk markers in elite rugby union athletes of Caucasian and Polynesian descent
Authors: Zemski Adam J. , Keating Shelley E. , Broad Elizabeth M. , Marsh Damian J. , Hind Karen , Walters Kylie J. , Slater Gary J.
Published: August 2019

Polynesian individuals are leaner with greater musculature than Caucasians of an equivalent size, and this genetically different morphology provides a physique that is often compatible with success in a number of sports, including rugby union. Evidence indicates that Polynesians have greater stores of absolute and relative abdominal fat mass and this is known to confer cardiometabolic risk. The aims of this study were to (1) explore the relationship between ethnicity, visceral adipose tissue (VAT), and cardiometabolic disease risk markers in elite Caucasian and Polynesian rugby union athletes, and (2) assess the impact of a pre‐season training programme on these markers. Twenty‐two professional rugby union athletes of Caucasian (n = 11) and Polynesian (n = 11) descent underwent physique assessment via surface anthropometry, dual‐energy X‐ray absorptiometry, and magnetic resonance imaging before and after an 11‐week pre‐season. A fasted blood test was undertaken at both time points. Compared to Caucasians, at baseline Polynesians displayed significantly higher VAT (771 ± 609 cm3 vs 424 ± 235 cm3; p = 0.043), triglycerides (1.0 ± 0.9 mmol/L vs 0.6 ± 0.2 mmol/L; p = 0.050), and low‐density lipoprotein cholesterol (3.1 ± 0.9 mmol/L vs 2.3 ± 0.7 mmol/L; p = 0.019). Similar changes were observed in both groups over the pre‐season period in VAT and blood biochemical markers. Polynesian rugby union athletes were more likely than Caucasians to exhibit risk factors associated with cardiometabolic disease, such as elevated VAT and unfavourable lipid profiles. Further longitudinal research is required to identify and explain the short‐ and long‐term risk of cardiometabolic disease in athletes of Polynesian descent.
Risk of Zika microcephaly correlates with features of maternal antibodies
Authors: Robbiani Davide F. , Olsen Priscilla C. , Costa Federico , Wang Qiao , Oliveira Thiago Y. , Nery Nivison , Aromolaran Adeolu , do Rosário Mateus S. , Sacramento Gielson A. , Cruz Jaqueline S. , Khouri Ricardo , Wunder Elsio A. , Mattos Adriana , de Paula Freitas Bruno , Sarno Manoel , Archanjo Gracinda , Daltro Dina , Carvalho Gustavo B.S. , Pimentel Kleber , de Siqueira Isadora C. , de Almeida João R.M. , Henriques Daniele F. , Lima Juliana A. , Vasconcelos Pedro F.C. , Schaefer-Babajew Dennis , Azzopardi Stephanie A. , Bozzacco Leonia , Gazumyan Anna , Belfort Rubens , Alcântara Ana P. , Carvalho Gustavo , Moreira Licia , Araujo Katiaci , Reis Mitermayer G. , Keesler Rebekah I. , Coffey Lark L. , Tisoncik-Go Jennifer , Gale Michael , Rajagopal Lakshmi , Adams Waldorf Kristina M. , Dudley Dawn M. , Simmons Heather A. , Mejia Andres , O’Connor David H. , Steinbach Rosemary J. , Haese Nicole , Smith Jessica , Lewis Anne , Colgin Lois , Roberts Victoria , Frias Antonio , Kelleher Meredith , Hirsch Alec , Streblow Daniel N. , Rice Charles M. , MacDonald Margaret R. , de Almeida Antonio R.P. , Van Rompay Koen K.A. , Ko Albert I. , Nussenzweig Michel C.
Published: August 2019

Zika virus (ZIKV) infection during pregnancy causes congenital abnormalities, including microcephaly. However, rates vary widely, and the contributing risk factors remain unclear. We examined the serum antibody response to ZIKV and other flaviviruses in Brazilian women giving birth during the 2015–2016 outbreak. Infected pregnancies with intermediate or higher ZIKV antibody enhancement titers were at increased risk to give birth to microcephalic infants compared with those with lower titers (P < 0.0001). Similarly, analysis of ZIKV-infected pregnant macaques revealed that fetal brain damage was more frequent in mothers with higher enhancement titers. Thus, features of the maternal antibodies are associated with and may contribute to the genesis of ZIKV-associated microcephaly.
Cyclic AMP links glucose stimulation to somatostatin secretion in δ-cells
Authors: Tengholm Anders
Published: August 2019

Tengholm reflects on new work providing insight into the mechanisms of glucose-stimulated somatostatin secretion from δ-cells.
Power law error growth in multi-hierarchical chaotic systems—a dynamical mechanism for finite prediction horizon
Authors: Brisch Jonathan , Kantz Holger
Published: August 2019

We propose a dynamical mechanism for a strictly finite prediction horizon, i.e. a scenatio of chaotic motion where asymptotically a more precise knowledge of the initial condition does note translate into a longer closeness of the forecast to the truth. For this, we propose a class of hierarchical dynamical systems which possess a scale dependent error growth rate in the form of a power law. Actually, this is motivated by and consistent with well known hierarchies of patterns in atmospheric dynamics. This scale dependent error growth rate in form of a power law translates in power law error growth over time instead of exponential error growth as in conventional chaotic systems. The consequence is a strictly finite prediction horizon, since in the limit of infinitesimal errors of initial conditions, the error growth rate diverges and hence additional accuracy is not translated into longer prediction times. By re-analyzing data of the National Center for Environmental Protect Global Forecast System, a weather prediction model, published by Harlim et al (2005 Phys. Rev. Lett.
94 228501) we show that such a power law error growth rate can indeed be found in numerical weather forecast models and estimate it average maximal prediction horizon to about 15 d.
Parameter identification and state-of-charge estimation approach for enhanced lithium–ion battery equivalent circuit model considering influence of ambient temperatures*
Authors: Pang Hui , Mou Lian-Jing , Guo Long
Published: August 2019

It is widely accepted that the variation of ambient temperature has great influence on the battery model parameters and state-of-charge (SOC) estimation, and the accurate SOC estimation is a significant issue for developing the battery management system in electric vehicles. To address this problem, in this paper we propose an enhanced equivalent circuit model (ECM) considering the influence of different ambient temperatures on the open-circuit voltage for a lithium–ion battery. Based on this model, the exponential-function fitting method is adopted to identify the battery parameters according to the test data collected from the experimental platform. And then, the extended Kalman filter (EKF) algorithm is employed to estimate the battery SOC of this battery ECM. The performance of the proposed ECM is verified by using the test profiles of hybrid pulse power characterization (HPPC) and the standard US06 driving cycles (US06) at various ambient temperatures, and by comparing with the common ECM with a second-order resistance capacitor. The simulation and experimental results show that the enhanced battery ECM can improve the battery SOC estimation accuracy under different operating conditions.
Comparison of crash behaviour prediction of a car crash box using initial and updated finite element model
Authors: Abdullah N.A.Z. , Sani M.S.M. , Salwani M.S.
Published: August 2019

Topic of crashworthiness is gaining popularity as vehicle safety is becoming main concern to the vehicle manufacturers worldwide. Due to this factor, energy absorbing members on vehicle such as crash box is researched by many which lead to various strategies of design optimization has been carried out in order to seek a good energy absorber on vehicle. Among the popular method of determining the crash performance of a structure is by using dynamic analysis in computational finite element model (FEM). However, since finite element analysis (FEA) is only an approximation method which in many cases can be less reliable, model updating method is often suggested to improve its reliability. This study seeks to investigate the crash behaviour of initial and updated crash box model. The velocity of impactor, the deformation, collapse distance and energy transferred to the two models of crash box are compared. The findings show that the initial and updated model of the crash box in this study, do have different crash behaviour. However, the difference level is relatively small. The investigation on the method of validation for the updated model in terms of crash behaviour is highly recommended.
A Comparative Study of CWELD and ACM2 Element Connectors on the Dynamic Behaviour of a Laser Spot Welded Hat-Plate Structure under Initial Stress Influence
Authors: Peter C , Rani M N Abdul , Hashim H , Yunus M A , Machmud M.N , Mohd Zin M S
Published: August 2019

Analytical modelling of the dynamic behaviour of a laser spot welded structure can be developed using two element connectors which are CWELD and ACM2. In the presence of initial stress in the structure, the performance of these two connectors can be different. In order to properly investigate the dynamic behaviour of the structure, the difference of these two element connectors in representing the laser spot welded in the structure should be evaluated. The finite element method was used to develop the welded structure comprising two structural components. The element connectors were then used to represent the laser spot welds in the structure. Normal modes analysis was performed on the FE model of the welded structure to calculate the modal parameters. Experimental modal analysis was carried out to measure the modal parameters of the physical welded structure. The modal parameters calculated from the two different FE models were evaluated by the experimental counterparts in terms of natural frequencies, mode shapes and MAC value. The accumulated error registered from all 6 modes from the CWELD element connector FE model is 10.59%. Meanwhile, the accumulated error calculated from all 6 modes of the ACM2 element connectors based FE model is 26.67%. It was found that the FE model with CWELD element connectors has shown a good correlation with the physical welded structure. The findings can have an important effect on how analytical modelling of the dynamic behaviour of the welded structure under initial stress can be effectively and accurately carried out.
Identifying the Appropriate Frequency Response Function Driving Point of a Car Door Using Finite Element Analysis and Modal Testing
Authors: Iskandar Mirza W I I Wan , Rani M N Abdul , Musa M F , Yunus M A , Peter C , Shah M A S Aziz
Published: August 2019

Identifying the appropriate frequency response function (FRF) driving point of complex structures is crucial to experimental modal analysis (EMA), but it is often found to be challenging and problematic. Traditionally, EMA analysts tend to place a reference sensor at several potential driving points and excite the points during testing. However, the approach is time-consuming. The aim of this work is to demonstrate an effective procedure for identifying the appropriate FRF driving point of a complex structure using finite element pre-test analysis and modal testing. The demonstration is performed on a car door structure comprising several geometrically complex structural components. The effective impedance method (EIM) is used to identify thirty potential driving points from the finite element model of the car door. The FRF data of the driving points is derived by using the FRF synthesis method and the derived data is compared with the EMA FRF data for validation purposes. Using EIM, three appropriate driving points covering all the modes required within the frequency of interest that is 0 to 100Hz has been successfully identified. The achievement suggests that the use of the effective impendence method for identifying the appropriate driving points is highly dependent on the accuracy and reliability of the finite element model.
Noise Source Identification of Automotive Radiator by Using Sound Intensity Mapping Method
Authors: Razak N F D , Sani M S M , Azmi W H , Zhang B
Published: August 2019

Automotive radiator played an essential role as a heat exchanger that exchange the circulated heated coolant inside the engine compartment to return into its ambient temperature. Radiator cooling fan that attached at the back of radiator, is a device that work to regulate the coolant temperature when the heated coolant is passed inside the radiator tubes. It produces external flow of air that passes through the fins and tubes of the radiator. However, this external flow contributes high noise level into the system. In consequence of this risk, a detailed experimental study on noise analysis to identify the location of maximum sound pressure level (SPL) generated by variations of cooling fan speed by using sound intensity mapping method is presented. Ethylene Glycol (EG)-water based was used as working fluid operate with engine temperature range from 80 to 90 °C. The cooling fan speed of radiator cooling fan were varied from 750 to 1250 rpm and the water flowrates were 8.0, 11.0, and 14.0 l/min. The results indicate that the noise level is increasing with the fan speed. However, there is no significance difference of change in coolant flow rate and type of coolant fluids to the noise level. The location of maximum sound pressure level is identified and the higher SPL value most located on the blade trailing edge of the suction surface with highest SPL value of 81 db for 1250 rpm fan speed. The project delivers the reliable input for the engineering practice to reduce automotive radiator noise level.
Potential of Using Natural Fiber for Building Acoustic Absorber: A Review
Authors: Taiwo Esan Martins , Yahya Khairulzan , Haron Zaiton
Published: August 2019

Sustainability is one of the significant goals in the evaluation and promotion of building materials in the current society. This paper presents an evaluation of the potential of natural fiber for building acoustics absorber. This was done by comparing all aspects of sustainability including economy, social and environmental needs between the natural and synthetic fibers. Some features of natural fibers such as light weight, bio-degradability, low-cost, carbon-dioxide neutral, low consumption of energy and health aspects has been the major factors that contributed to its use in many construction applications. In addition to that, previous researches showed that sound absorbing materials with natural fibers have good acoustic properties in high frequency range similar with those synthetic fiber. However, high water absorption, prone to termite attack, less fire resistance and low strength are remaining the issues militating against the natural fiber for building acoustic absorber. Despite that, natural fibers have already been proven alternatives to synthetic fiber in building acoustic absorber thereby alleviating some sustainability issues associated with the use of synthetics materials in building acoustics.
Joining Strategy Analysis of Structural Dynamic in Top Hat Plate of Dissimilar Materials
Authors: Nazri N.A. , Sani M.S.M.
Published: August 2019

Structural dynamic can be described as a study regarding analysis of model under exertion of dynamic loading. Joining in structure such as riveting, welding and soldering were strongly effects the structural dynamic properties. The aim of this paper is to conduct various joining strategy analysis in finite element software by using top hat plate structure in car as a model and result is compared with experimental data. Normal mode analysis with free-free boundary condition is applied. Resistance spot welding (RSW) technique is selected to weld flange part in top hat plate between dissimilar materials which is mild steel 1010 and stainless steel 304 with specified parameters applied. Modal testing via impact hammer test is carried out at the welded top hat plate for experimental analysis purpose. Correlation in between FEA and EMA results need to be conducted. By selecting identified parameters to execute model updating on the structure using sensitivity analysis method, the discrepancies in natural frequencies were reduced between FEA and EMA. CWELD element was chosen to represent weld model for spot weld joints due to its accurate prediction of frequencies and mode shapes compare to other weld modelling. As a closure, connection in structure parts play significant role in structural dynamics and model updating is one of successful method to lessen the discrepancies between FEA and EMA.
Model Updating of Frame Structure with Bolted Joints
Authors: Izham M.H.N. , Sani M.S.M.
Published: August 2019

Experimental analysis is often viewed as an important source of reference compared to finite element due to the accuracy of giving reliable data. Currently, finite element analysis is widely used as an early adoption in development, hence trusting the finite element data is crucial for the user. Finite element analysis often shows discrepancies to the test result. The complexity of the joints (bolted) might cause the discrepancies to occur. This study aims to reduce the discrepancies between the experimental and numerical analysis on a frame structure with bolted joints by model updating. Model updating is a process of making adjustment to certain parameters of finite element model to reduce discrepancy between analytical predictions of finite element analysis (FEA) and experimental results. Modal properties (natural frequencies, mode shapes, and damping ratio) of a frame structure with bolted joints are determined using both experimental modal analysis (EMA) and finite element analysis (FEA). Both data obtained is correlated before optimising the properties with sensitivity analysis. Joint strategy of this paper is focusing on RBE2, CBAR and CELAS element. CELAS was selected to represent the bolted modelling due to its lowest percentage average of 2.03% compares to CBAR 6.55% or RBE2 3.56%. Selected parameters were identified by performing a sensitivity analysis and the discrepancies was reduced by performing model updating procedure.
Predicting the Dynamic Stiffness of a Glove Material using Mechanical Impedance Model
Authors: Razali K. A. Md , Samin R. , As’arry A. , Jalil N. A. A.
Published: August 2019

Anti-vibration glove has been developed to be able to attenuate vibration transmitted to the hand. However, the performance depends on lots of factors such as the contact area and contact force. In addition, the materials used in gloves are commonly made of foam and gel, which produce complex response when these factors are changed. This study aimed to predict the dynamic stiffness of a glove based on the measured transmissibility and apparent mass, using mechanical impedance model. This is used so that the dynamic response of the material can be well understood when parameters such as contact area and contact force are changed. The mechanical impedance model has previously been used to predict transmissibility and showed prediction that is comparable to the measured transmissibility. Measured transmissibilities and apparent masses of the hand of five subjects were used in the model to predict the dynamic stiffness of the glove material. The predicted dynamic stiffness was then compared to the dynamic stiffness measured experimentally. The results showed that the predicted dynamic stiffnesses were similar to the measured dynamic stiffness. In conclusion, the mechanical impedance model is able to predict dynamic stiffness of the glove material.
Stability analysis of regenerative vibration in turning operation using I-kaz3DTM signal processing approach
Authors: Samin R , Nuawi M Z , Haris S M , Ghani J A
Published: August 2019

This paper presents a stability analysis to predict regenerative vibration during turning process. Although the stability of machining process has been widely studied in metal cutting it still presents a challenge as surface roughness, tool wear and productivity have to be considered. If the tool is vibrating as it removes material, these vibrations are imprinted on the workpiece surface as a wavy profile. However, the relative phasing between the surface waviness from one pass to the next determines the level of force variation and whether the operation is stable or unstable. Then we investigate the unstable and stable phenomena during the machining process by discussing the number of time-domain simulation to determine the force and surface roughness values these stability thresholds. A signal processing was carried out using I-Kaz3D technique to identify the effect between the unstable and stable phenomena. The results show that the relationship between I-kaz3D coefficients and surface roughness values can be considered very highly correlated.
Training Feedforward Neural Networks for Structural Health Monitoring of an Aircraft Structure
Authors: Rahman Tuan A Z , Rezali K A M , Jalil N A Abdul , As’arry A , Kamil Raja
Published: August 2019

In the past decades, structural health monitoring (SHM) has become an emerging research area for globally monitoring expensive aircraft and bridge structures. This paper presents the application of stochastic fractal search (SFS) algorithm and its chaotic-enhanced variants to train feedforward neural networks (FNNs) for monitoring an aircraft structure based on vibration data. An experimental spectral testing was carried out to obtain the normal and damaged condition data of a laboratory stiffened panel structure which imitated wingbox of an aircraft. Added mass as pseudo-fault was employed to simulate damage condition with three different damage levels at three different locations. Vibration signature features were generated based on measured frequency response functions (FRFs) and principle component analysis (PCA). Then, metaheuristic-based FNNs approach were applied to localize and predict the severity of damage on the structure. The results reveal that the proposed approach produces high classification and localization accuracy as parameters of the FNNs were optimized systematically using metaheuristic algorithms. In conclusion, the Sine chaos-enhanced SFS algorithm highlights better convergence performance and results accuracy compared to other contested metaheuristic approaches.
In-situ observations of dislocation recovery and low angle boundary formation in deformed aluminium
Authors: Ånes H W , van Helvoort A T J , Marthinsen K
Published: August 2019

An experimental study of the recovery of dislocations and low angle boundary formation in aluminium is presented. By combining in-situ annealing with orientation mapping in the transmission electron microscope, maps of geometrically necessary dislocation estimates derived from orientation measurements and subgrain formation can be quantitatively analysed. A thin foil of a commercially pure aluminium alloy cold-rolled to a true strain of ε = 2.3 and annealed in-situ in four steps of increasing temperatures from 170 °C to 560 °C was studied. An increase in the subgrain size and low angle boundary misorientation was accompanied by a halving of the dislocation density from 1.2 × 1016 m−2 to 0.6 × 1016 m−2. Limited boundary migration was observed and the increased subgrain size was attributed to the dissolution of dislocations within the low angle boundaries upon annealing.
Non-destructive texture measurement methods for centreless X-ray diffractometers in reverse modified X (CHI) mode
Authors: Mertinger V , Sepsi M , Benke M
Published: August 2019

Conventional X-ray diffraction-based pole figure measurements have been carried on with dedicated instrument which are accompanied with certain limitations such as sample size, geometry, and no possibility for on-site measurements. These restrictions limit the availability of texture measurements to situations in which cutting a small sample from large parts is difficult or even not allowed at all. The present paper introduces new texture measurement method developed on mobile centreless X-ray diffractometers which are originally applied for residual stress measurements. The essence of this new method, named reverse modified X mode is that it uses the data obtained by residual stress measurement to describe anisotropic characteristics, even to the determination of pole figure. Using this method, pole figures can be obtained with all the benefits of centreless diffractometers: no need for sample cutting, flexibility in case of large components with complex shapes, short measuring time and portability. The obtained pole figures are equivalent to the pole figures determined by conventional diffractometers. The presentation describes the measurement method and includes the validation with conventional pole figure measurements and provides instances of applications of the new technique.
A study of the static recrystallization behaviour of cast Alloy 825 after hot-compressions
Authors: Al-Saadi M , Sandberg F , Hulme-Smith C , Karasev A , Jönsson P G
Published: August 2019

The static recrystallization behaviour of a columnar and equiaxed Alloy 825 material was studied on a Gleeble-3800 thermo-simulator by single-hit compression experiments. Deformation temperatures of 1000-1200 °C, a strain of up to 0.8, a strain rate of 1s−1, and relaxation times of 30, 180, and 300 s were selected as the deformation conditions to investigate the effects of the deformation parameters on the SRX behaviour. Furthermore, the influences of the initial grain structures on the SRX behaviors were studied. The microstructural evolution was studied using optical microscopy and EBSD. The EBSD measurements showed a relaxation time of 95 % for fractional recrystallization grains, t

95
, in both structures, was less than 30 seconds at the deformation temperatures 1100 °C and 1200 °C. However, fewer than 95% of recrystallized grains recrystallized when the deformation temperature was lowered to 1000 °C. From the grain-boundary misorientation distribution in statically recrystallized samples, the fraction of high-angle grain boundaries decreased with an increasing deformation temperature from 1000 °C to 1200 °C for a given relaxation time. This was attributed to grain coarsening.
The assessment of growth kinetics in the intermetallic layers of Al-AlxNiy-Ni laminate composites
Authors: Azimi M , Toroghinejad M R , Shamanian M , Kestens L A I
Published: August 2019

Ni aluminides have technologically attracted much attention as oxidation protective layers on Ni-superalloys for high-temperature and harsh environments applications as well as for reinforcements in metal-matrix composites. Among the Ni aluminides, the AlNi compound exhibits the best combination of oxidation-protective characteristics and hardness; thus there is a progressive demand to produce it particularly through convenient in-situ fabrication processes. Therefore, the evaluation of growth kinetics in AlxNiy layers is of crucial importance in determining an optimum compound formation process. To this purpose, Al-Ni intermetallic laminate composites were produced through cold roll bonding and subsequent annealing of aluminum and nickel sheets. The microstructure of the intermetallic layers was investigated in order to specify the controlling mechanisms and subsequently the growth model of the different phases. The Al3Ni layer was kinetically the first to appear but started to decompose at the expense of the AlNi compound when the direct source of Al disappeared for the reactive diffusion couples. The Al3Ni layer growth was initially controlled by bulk diffusion, but then at T≥525°C was modified as a function of competition between formation and consumption, whereas the AlNi growth was governed strongly by the interfacial reaction. The time dependence of the growth rate revealed different behaviors of linear and parabolic kinetics. The overall assessment revealed a bulk diffusion-controlled growth for all of the intermetallic layers. Arrhenius parameters could be derived for the Al3Ni layer, while it was impossible for the AlNi phase because the formation of this layer was caused by a mixture of diffusion mechanism.
Simulation of deformation and static recrystallization in the stress relaxation test
Authors: Seppälä O , Pohjonen A , Ilmola J , Jokiranta A , Kaijalainen A , Somani M , Larkiola J
Published: August 2019

A finite element (FE) simulation model illustrating the stress relaxation test was established with the Abaqus
TM
software. The microstructural evolution of steel during relaxation includes the complex phenomena of recrystallization. While the compression introduces the planned deformation and stress into the test piece, subsequent softening relieves the stress and at the same time creates microstructural reconstitution and refinement. In this study, a model was developed to simulate the kinetics of static recrystallization taking place during holding, using a technique based on FE-simulation. The simulation results have been compared to the experimental stress relaxation data obtained on a Gleeble
TM
3800 thermo-mechanical simulator. The model can be used to estimate the recrystallization kinetics throughout the test piece. In the future, these results can be used for estimating the required rolling forces for multi-pass roughing with reasonable accuracy, for instance. The modelling methodology can be extended to other steels too, with or without microalloying additions.
The effect of Niobium on Austenite Evolution during Hot Rolling of Advanced High Strength Steel
Authors: Smith A , Vercruysse F , Petrov R , Verleysen P
Published: August 2019

Two AHSS steels (0.2C-2.4Mn-1.5Si with/without Nb+Cr addition) were subjected to pilot reversing mill hot rolling in 5 passes varying the finish rolling and coiling temperature. After coiling simulation, the final microstructures were characterised by the EBSD technique measurements. One sample was analysed to determine the presence and the level of Nb precipitated by TEM and chemical extraction. The austenite evolution was inferred from the measured transformation textures and reconstructed final austenite texture and microstructure. Further insights were obtained by comparing the results to a semi-empirical austenite evolution model, which predicted recrystallization behaviour and level of Nb precipitation. From the combined experimental and modelling work it was shown that Nb addition led to recrystallization inhibition via partial strain induced precipitation for this high Mn and high Si steel. Applying the austenite evolution model to a more realistic industrial hot strip rolling schedule revealed earlier Nb precipitation during hot rolling and higher strain accumulation with a finer grain size. The final Nb level in solution was lower for the industrial schedule, although a significant amount was not precipitated (two thirds of the total).
Effect of Thermomechanical Parameters on Grain Growth and Recrystallization during Grain Boundary Engineering of Austenitic Stainless Steel
Authors: Tokita Shun , Kokawa Hiroyuki , Sato Yutaka S.
Published: August 2019

Grain boundary engineering has been attracting attention as an effective method to prevent intergranular corrosion of austenitic stainless steel and Ni based alloys. It has been considered that grain growth and recrystallization play important role in evolution of grain boundary character distribution during thermomechanical process. However, systematic researches to examine the effect of thermomechanical process parameters on grain growth and recrystallization have not been performed. In this study, grain boundary character distribution of 304 austenitic stainless steel after thermomechanical process with various parameters was analysed by electron backscatter diffraction (EBSD). Grain boundary character distribution was mainly affected by the reduction ratio of cold rolling. Abnormal grain growth was observed in the specimen with small reduction ratio (3%). Length ratio of coincident site lattice (CSL) boundaries was drastically increased to 86% in the 3% cold rolled and annealed specimens from 67% in the base material. On the other hand, normal grain growth was observed in thermomechanical processed specimens with slightly higher reduction of cold rolling (5%). In these specimens length ratio of CSL boundaries did not exceed 80%, which is required to disconnect the random boundary networks and to improve intergranular corrosion resistance effectively. Detailed analysis of grain boundary character distribution has shown that disconnection of random boundary networks was achieved by formation of annealing twins during abnormal grain growth.
Evaluation of the kinetics of recrystallization based on scaling 1D cellular automaton by DSC measurements
Authors: Bubonyi Tamás , barkóczy Péter , Gyöngyösi Szilvia
Published: August 2019

There are several methods to study the kinetics of the recrystallization process. DSC measurement is one of the most effective measurement methods. Cellular automata simulations are frequently used in computational studies. Both methods give and use kinetic constants. The aim of this study to find the relation between the kinetic constants. Additionally an evaluation method is introduced based on the DSC evaluation and cellular automaton which can compute a more detailed kinetic description of recrystallization.
Limit conditions for the onset of abnormal grain growth in a homogeneous microstructure: Theory and Experiments
Authors: Abbruzzese GC
Published: August 2019

In previous papers it has been demonstrated that abnormal grain growth in a polycrystalline microstructure is a natural phenomenon even in the presence of an homogeneous microstructure. Namely, in a statistical sense, each portion of the material has the same grain size distribution and no local heterogeneities are involved. The only necessary condition is the presence of a grain growth inhibitor which can be represented by second phase particles (Zener Drag), homogeneously distributed as well, or by segregating atoms on the grain boundary (Atoms drag).

Considering specifically the Zener Drag effect, it can be shown that in the presence of an evolution of the restraining force ( even if extremely slow), due to Ostwald ripening or to dissolution of the particles, the corresponding grain growth process allows the grain size distribution to continuously evolve reaching a critical shape. Such peculiar shape corresponds to a “structural” instability which irreversibly determines the onset of an abnormal growth phase with a drastic change of grain growth kinetics (kinetics exponents for the mean radius largely above the canonical 0.5).

In this context the mechanism of Abnormal Grain Growth onset is discussed as a general physical phenomenon and a set of experimental data on several steels will be presented for supporting such conclusion.
Influence of a pre-deformation on the growth of titanium multicrystals
Authors: Chaubet D , Beucia W , Franciosi P , Bacroix B
Published: August 2019

In the present study, we have developed a new elaboration process which facilitates the growth of titanium single crystals by combining plastic strain and thermal cycling around the transition temperature. It consists in introducing a small plastic deformation into annealed specimens (like in the critical strain hardening method) before carrying out annealing cycles of only a few days under high vacuum. This method has been applied to titanium of commercial purity (CP-Ti). At the end of each cycle, samples are examined in SEM / EBSD for the characterization of grain sizes and shapes, crystallographic orientations and crystalline quality.

Our first results demonstrate that we can obtain grains bigger than one square centimetre (thickness 2mm) after a preliminary plastic deformation of 3% followed by two 2 pairs of annealing cycles (total time: 96 hours). This enhanced growth is thought to be due to the combination of two driving forces associated (i) to the energy stored within the grains during plastic strain and (ii) to the phase transformation, which acts alone in the transus cycling process. These single crystals are intended to be used to study their mechanical behaviour with the small tensile machines developed to perform in situ mechanical tests into microscopes (SEM, AFM) or diffractometers.
A continuous dynamic recrystallization model to describe the hot deformation behaviour of a Ti5553 alloy
Authors: Buzolin R H , Krumphals F , Lasnik M , Krumphals A , Poletti M C
Published: August 2019

A physical based model is developed to describe recrystallization phenomena of titanium alloys during hot working of the β phase. Continuous dynamic recrystallization is attributed as the restoration mechanism based on the progressive transformation of low angle boundaries (subgrains) into high angle boundaries (grains). The model describes both, the microstructure, and the flow stress evolutions during hot deformation with large strains. The microstructure is conceived as been formed by three different populations of dislocations, and high as well as low angle grain boundaries. Evolution rates of all microstructural features are determined based on the effects of generation, interaction and annihilation of dislocations during deformation due to dynamic recovery, continuous dynamic recrystallization and static recovery. Continuous dynamic recrystallization is modelled and is considered to occur homogeneously within the microstructure. The model is able to predict the formation of subgrains from a fully annealed microstructure and the progressive formation of high angle grain boundaries. The subgrain and grain sizes are also obtained as output of the model. The model was applied to describe the hot compression behaviour of a Ti5553 alloy deformed between 880°C to 920°C and strain rates from 0.001 s−1 up to 10 s−1. The model is validated with flow curves and microstructural characterisation of hot deformed, and with microstructural information of non-deformed samples. The critical strain rate increases with increasing strain rate and decreasing temperature, similar to the discontinuous dynamic recrystallization phenomenon. The model can be implemented to simulate the microstructure and predict flow stresses of titanium alloys in industrial processes.
Consideration of recrystallization modeling of γ/γ’-strengthened Ni-based superalloys at sub-solvus temperatures
Authors: Nishimoto Takashi , Okajima Takuma , Zhang Qiaofu , Gong Jiadong , Olson Greg
Published: August 2019

New Ni-based superalloys and methods for controlling their microstructures have recently received much investigation to further improve their high-temperature properties, sometimes via control of precipitates such as γ’ (Ni3(Al,Ti,Nb,Ta)) and γ″ (Ni3Nb). In Ni-based superalloys, fine grains favor deformability and mechanical properties; therefore, control of grain size, achieved by recrystallization, is also important. Some new studies have reported the pinning effects of coarse γ’. However, few studies have investigated modeling methods for recrystallization behaviors. Difficulties in grain size and phase distribution control have hindered fabrication by open-die forging utilizing the pinning effect of the γ#x2019; phase. Therefore, this study examines the recrystallization behaviors of Ni-based superalloys containing coarse primary γ’ precipitates and considers applicable modeling methods. The recrystallization behaviors at sub-solvus temperatures are investigated in a new Ni-based superalloy with abundant coarse γ’ precipitates. Grain growth is limited by the pinning effect of coarse γ’ and the recrystallized grain size corresponds to increasing applied strain. Dynamic and static recrystallization is promoted by high strains and high temperatures. The kinetics of the recrystallized area fraction and recrystallization grain growth influenced by the pinning effect of coarse γ’ is modeled by Zurob’s method.
Kinetics of recrystallization and grain growth in an ultra-fine grained CoCrFeNiMn-type high-entropy alloy
Authors: Klimova M V , Shaysultanov D G , Chernichenko R S , Sanin V N , Zherebtsov S V , Stepanov N D
Published: August 2019

A novel high entropy alloy based on the CoCrFeMnNi system with substantial amounts of Al and C was studied. After cold rolling and annealing at 973-1273 K a duplex ultra-fine grained structure composed of the recrystallized fcc grains and M23C6 and B2 particles was produced. Analysis of the coarsening behavior of grains and particles growth suggested that kinetics of both was controlled by volume diffusion. The apparent activation energy of structure coarsening during recrystallization was evaluated.
A biohybrid fly-robot interface system that performs active collision avoidance
Authors: Huang Jiaqi V , Wei Yiran , Krapp Holger G
Published: August 2019

We have designed a bio-hybrid fly-robot interface (FRI) to study sensorimotor control in insects. The FRI consists of a miniaturized recording platform mounted on a two-wheeled robot and is controlled by the neuronal spiking activity of an identified visual interneuron, the blowfly H1-cell. For a given turning radius of the robot, we found a proportional relationship between the spike rate of the H1-cell and the relative distance of the FRI from the patterned wall of an experimental arena. Under closed-loop conditions during oscillatory forward movements biased towards the wall, collision avoidance manoeuvres were triggered whenever the H1-cell spike rate exceeded a certain threshold value. We also investigated the FRI behaviour in corners of the arena. The ultimate goal is to enable autonomous and energy-efficient manoeuvrings of the FRI within arbitrary visual environments.
Forest loss in Brazil increases maximum temperatures within 50 km
Authors: Cohn Avery S , Bhattarai Nishan , Campolo Jake , Crompton Octavia , Dralle David , Duncan John , Thompson Sally
Published: August 2019

Forest cover loss in the tropics is well known to cause warming at deforested sites, with maximum temperatures being particularly sensitive. Forest loss causes warming by altering local energy balance and surface roughness, local changes that can propagate across a wide range of spatial scales. Consequently, temperature increases result from not only changes in forest cover at a site, but also by the aggregate effects of non-local forest loss. We explored such non-local warming within Brazil’s Amazon and Cerrado biomes, the region with the world’s single largest amount of forest loss since 2000. Two datasets, one consisting of in-situ air temperature observations and a second, larger dataset consisting of ATs derived from remotely-sensed observations of land surface temperature, were used to quantify changes in maximum temperature due to forest cover loss at varying length-scales. We considered undisturbed forest locations (1 km2 in extent), and forest loss trends in annuli (‘halos’), located 1–2 km, 2–4 km, 4–10 km and 10–50 km from these undisturbed sites. Our research finds significant and substantial non-local warming, suggesting that historical estimates of warming due to forest cover loss under-estimate warming or mis-attribute warming to local change, where non-local changes also influence the pattern of temperature warming.