bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compensation of roundness deviations of bearing rings by heat treatment
Authors: Lütjens J. , Surm H. , Hunkel M. , Gafsi H. , Renken V. , Schüttenberg S. 
Published: January 2012

AbstractThe compensation of distortion of 100Cr6 (SAE 52100) bearing rings can be achieved within each of the production chain steps turning, austenitisation, and quenching. This work evaluates the compensation potential during heat treatment. For this purpose, rings are austenitised in a bottom‐loading furnace with six individually controlled heating elements. Temperature distributions in the rings during heating and soaking are used to influence the local solute carbon content. After austenitisation, the rings are quenched in a gas nozzle field with 13 individually controlled quenching zones, one on the inner surface and 12 on the outer surface of the ring. The roundness deviation just before quenching is measured using tactile sensors. The heat treated parts are examined with regard to distortion but also to the requirements of hardness, microstructure, and residual stresses. Limits of roundness deviation compensation in different Fourier orders are evaluated.
Experimental investigation concerning the development of distortion potential during the production of 20MnCr5
Authors: Prinz C. , Rentsch R. 
Published: January 2012

AbstractInvestigations within the SFB 570 “Distortion Engineering” showed that properties of the low alloyed 20MnCr5 (SAE 5120) had an influence on distortion. The changes of curvature of blind‐hardened shafts could be correlated to a macroscopic structure, which was visible at micrographs of cross‐sections. The development of lined structures and the macroscopic structure was observed by metallographic methods at cast material, hot‐rolled material and an intermediate step of the hot forming process. The lined structure within the semi‐finished material was measured by EPMA measurements with highest resolution. The contents of the alloying elements Mn and Cr could be correlated to the development of the lined structure, the carbon content fluctuated in a higher frequency. To determine the differences of phase transformations, two different homogenous materials were produced by spray‐forming: one with the maximum content of the alloying element Mn, Cr and C concerning the EPMA measured values, and a second with the minimum measured Mn, Cr and C content. The material was hot formed to a diameter of 25 mm after spray‐forming and characterised by dilatometer measurements.
Finite element analysis of the hot rolling process on the origins of inhomogeneities related to steel bar distortion
Authors: Rentsch R. , Prinz C. 
Published: January 2012

AbstractRecent analyses of the distortion of shafts made of the steel 20MnCr5 showed a bending along their length axis. Metallographic analyses revealed remarkable concentration fluctuations of Manganese and Chromium in the shaft center, which could be attributed to macro‐segregations. Its characteristic rectangular shape correlated with the direction of shaft bending. In order to understand the origin of the rectangular segregation in shafts manufactured from hot‐rolled round bars and to determine the influence of the forming process on the found distribution, a Finite element (FE) analysis of the whole hot‐rolling process was carried out. The results show a significantly inhomogeneous strain distribution at the shaft cross‐section, which provides a distortion potential for a preferred shaft bending direction. Further it was found, that the forming process influences the shape of the macro‐segregation in the shaft center, but the analysis hints in this case on an origin of the rectangular macro‐segregation in continuous casting.
Influence of manufacturing parameters on gear distortion
Authors: Kohlhoff T. , Prinz C. , Rentsch R. , Surm H. 
Published: January 2012

AbstractRealising the system‐oriented approach of “Distortion Engineering”, the influence of multiple parameters on the distortion of cylindrical gears was investigated by design of experiments. Aim of this research work was to investigate the effect of production parameters before the final heat treatment. The established experimental design focuses on the analysis of two main parts of gear distortion. One part is the distortion of the teeth themselves; the other part is a displacement of the teeth due to the distortion of the disk‐shaped base body. The selection of the varied parameters is partly based on results of a system‐oriented experiment with disks. Therefore several influences on the base body distortion are known. In comparison to the analysis of disk distortion the interpretation of gear distortion measurements requires significantly extended effort. Besides a determination of the distortion of the complex involute tooth profile, it has to be distinguished between a change of the tooth profile and a change of the base body.
Methodical investigation of distortion biasing parameters during case hardening of spur wheels
Authors: Steinbacher M. , Surm H. , Clausen B. , Lübben Th. , Hoffmann F. 
Published: January 2012

AbstractHighly stressed gears are typically heat treated to satisfy operational demands. Case hardening is a common heat treatment associated with power train components. In the heat treatment process complex distortion processes take place, which were studied in these examinations. Object of the actual investigations were spur wheels with module 2.557 and 42 teeth on the wheel with a helix angel of 23°. The case hardening was realized utilizing low pressure carburisation with subsequent high pressure gas quenching in a heat treatment furnace of industrial proportion. The systematic analysis was guided using design of experiment methods. In strategic focus were the three contributing heat treatment steps of heating, carburisation and quenching. Heating related factors were the batch design, the heat transfer and the preheating temperature. During carburisation the temperature, carburisation depth and surface carbon content as well as the atmosphere during diffusion were altered. Finally the quenching related variation was the hardening temperature. The identified main factors on size as well as shape changes of the base body and the toothing will be presented and discussed.
Adapted spray quenching for distortion control
Authors: Schüttenberg S. , Lütjens J. , Hunkel M. , Fritsching U. 
Published: January 2012

AbstractFor the analysis of workpiece distortion activated during heat treatment processes, the hardening by quenching in flexible flow fields is modelwise described. Here, process conditions and the resulting heat transfer from workpiece surfaces to the quenching medium are crucial conditions for the description of the quenching process and a possibly appearing distortion. During the quenching process suitable distortion compensation can be realised by impressing controlled asymmetric heat transfer conditions on workpiece surfaces by the use of liquid jet or spray arrangements. Here, the controlled quenching in and with liquid media and especially the use of two phase atomisers for spray cooling processes enables the generation of specific local heat transfer conditions with required high intensities.
Strategies for reduced distortion during laser beam welding of shaft‐hub joints
Authors: Buschenhenke F. , Seefeld T. , Vollertsen F. 
Published: January 2012

AbstractThe joining of shaft‐hub connections is gaining in importance in the area of power train applications. The quality demands in abrasion and power transmission are playing a major role. Dimensional as well as repeat accuracies are essential quality criteria, which have to be focused on. The understanding of the whole process chain in view of different distortion potentials introduced in each processing step provides the ability to control the distortion of the welded components. The laser beam sources of the new generation permit a high power welding process and high beam quality at the same time. These laser beams are capable of producing deep and narrow weld seams. This work deals with compensation strategies of deformations during laser beam welding in axial welded shaft‐hub joints made of steel. Furthermore, simultaneous welding with two laser beams and the influence of the process chain were investigated to characterise the influence of these strategies tactile differential measurements were done. The results were discussed regarding numerical calculations in the FEM application SYSWELD.
Areal parameters for the characterisation of gear distortions
Authors: Stöbener D. , von Freyberg A. , Fuhrmann M. , Goch G. 
Published: January 2012

AbstractGear distortion is influenced by several effects which might originate in various steps of the entire production chain. To understand the distortion mechanisms including interactions between different influencing parameters, a system approach for the whole production process is required. As distortion is not constrained to the toothing but also effects the gear's base body, an extended measuring strategy (compared to the standard) has been devised. Based on this strategy, an areal evaluation has been developed and new quality parameters describing the deviations of the whole gear and of each tooth have been defined. In contrast to the standard evaluation, the new quality parameters consider the relationship between different measured lines. This offers the possibility to determine the influences of the base body deviations on the toothing distortion and to separate them from the intrinsic toothing deviation. This paper describes the developed strategies and methods and compares them with the standard inspection process.
Monitoring a laser beam heat treatment process by means of digital speckle photography
Authors: Kamau E. N. , Sakkiettibutra J. , Falldorf C. , Mundt J. , Kopylow C. v. 
Published: January 2012

AbstractIn the current study displacements of a single angled tooth (helical gear, steel EN 20MnCr5) were measured with sub‐pixel accuracy by means of Digital Speckle Photography (DSP). The main aim was to assess the in‐process performance of DSP while measuring three dimensional deformations in a laser based heat treatment process. This task dictated the integration of DSP as a non‐invasive experimental method, which is insensitive to different interfering effects, e. g. vibrations and varying coefficients of refraction, into the heat treatment setup. The results attained were compared with data from laser triangulation measurements and FEM‐based temperature simulations and were found to show good agreement within the limitations of these methods. Knowledge of deformations of the component during the laser beam based heat treatment process allows an analysis of the effects of residual stress fields generated with a high power laser. This analysis aims at minimisation of unwanted distortions resulting from hardening heat treatment.
Approaches to describe distortion along process chains
Authors: Thoben K.‐D. , Klein D. , Seifert M. , Wuest T. 
Published: January 2012

AbstractDuring the decade of the Collaborative Research Center CRC 570 “Distortion Engineering” many methods were developed and extended. Within this paper these methods are evaluated in respect of practical application in process planning. The methods can be arranged by two different targets. On the one hand by mainly consider distortion up to predict distortion to support planning. The similarity of all methods is given due to the fact that distortion has to be seen as a system attribute. After the introduction of the methods and their basic functionality they were evaluated against process planning in particular the planning types “repeat planning” up to “new planning”. Generally it can be shown that the transferability on other geometries, processes and materials is strongly limited. Furthermore the methods which only consider distortion seem better to fulfill the tasks of the planning types as methods which determine distortion. The best method was the method which compares different process chains. Nevertheless, this more theoretical evaluation has to be verified by industrial process planning.
Knowledge and planning system for distortion engineering
Authors: Thoben K.‐D. , Klein D. , Wuest T. , Zoch H.‐W. 
Published: January 2012

AbstractPresented will be a process‐oriented knowledge and planning system for a structured depositing and locating of findings along manufacturing processes for component distortion. In the focus of this article are the reasons for the chosen structure and the presentation of the model for implementation of this system. It is shown that the findings must be seen first in connection with a process chain. A further evaluation of the findings will show that information can then be generalised to sub‐process chains. The findings can be accessed from a knowledge perspective to be a basis of new experiments, but also be used for archiving of knowledge. The planning view for example is suitable to help a planner to set up a process plan. The system is designed in a way that it can be easily extended by new findings. Concluding, the functioning of the system will be illustrated by two practical examples.
Assessment of the high‐dose concept and level of control provided by MON 87701 × MON 89788 soybean against Anticarsia gemmatalis and Pseudoplusia includens (Lepidoptera: Noctuidae) in Brazil
Authors: Bernardi Oderlei , Malvestiti Glaucia S , Dourado Patrick M , Oliveira Wladecir S , Martinelli Samuel , Berger Geraldo U , Head Graham P , Omoto Celso 
Published: January 2012

AbstractBACKGROUND: Genetically modified MON 87701 × MON 89788 soybean (Glycine max), which expresses the Cry1Ac and EPSP‐synthase proteins, has been registered for commercial use in Brazil. To develop an Insect Resistance Management (IRM) program for this event, laboratory and field studies were conducted to assess the high‐dose concept and level of control it provides against Anticarsia gemmatalis and Pseudoplusia includens.RESULTS: The purified Cry1Ac protein was more active against A. gemmatalis [LC50 (FL 95%) = 0.23 (0.15–0.34) µg Cry1Ac mL−1 diet] than P. includens [LC50 (FL 95%) = 3.72 (2.65–4.86) µg Cry1Ac mL−1 diet]. In bioassays with freeze‐dried MON 87701 × MON 89788 soybean tissue diluted 25 times in an artificial diet, there was 100% mortality of A. gemmatalis and up to 95.79% mortality for P. includens. In leaf‐disc bioassays and under conditions of high artificial infestation in the greenhouse and natural infestation in the field, MON 87701 × MON 89788 soybean showed a high level of efficacy against both target pests.CONCLUSIONS: The MON 87701 × MON 89788 soybean provides a high level of control against A. gemmatalis and P. includes, but a high‐dose event only to A. gemmatalis. Copyright © 2012 Society of Chemical Industry
A new implementation of the adaptive mesh transform in the Met Office 3D‐Var System
Authors: Piccolo Chiara , Cullen Mike 
Published: January 2012

AbstractThis paper looks at the application of two new features of the adaptive mesh transform in the Met Office variational data assimilation which modifies the background error correlations to better represent the boundary layer structure. The new features are an improved normalization procedure and the recalculation of the adaptive mesh within the nonlinear analysis procedure. Relative to the initial implementation the results show improvements in the forecast skill of the UK4 model for both summer and winter and a reduction of the analysis root mean square errors with respect to radiosonde, aircraft, SEVIRI and ground GPS observations for both periods. Forecast errors at T + 2, 3, 4 h are also reduced with respect to aircraft, surface, SEVIRI, ground GPS observations and with respect to radiosonde in the boundary layer for relative humidity and for potential temperature around temperature inversions. These improvements are attributed to the variation of the background vertical correlations and the implied background error variances in the assimilation due to the greater movement of the mesh away from the lower boundary, in particular in areas where temperature inversions or stratocumulus layers are present. Copyright © 2012 British Crown copyright, the Met Office. Published by JohnWiley & Sons Ltd.
Relaxing the Tropics to an ‘observed’ state: analysis using a simple baroclinic model
Authors: Hoskins Brian , Fonseca Ricardo , Blackburn Mike , Jung Thomas 
Published: January 2012

AbstractThe technique of relaxation of the tropical atmosphere towards an analysis in a month‐season forecast model has previously been successfully exploited in a number of contexts. Here it is shown that when tropical relaxation is used to investigate the possible origin of the observed anomalies in June–July 2007, a simple dynamical model is able to reproduce the observed component of the pattern of anomalies given by an ensemble of ECMWF forecast runs. Following this result, the simple model is used for a range of experiments on time‐scales of relaxation, variables and regions relaxed based on a control model run with equatorial heating in a zonal flow.A theory based on scale analysis for the large‐scale tropics is used to interpret the results. Typical relationships between scales are determined from the basic equations, and for a specified diabatic heating a chain of deductions for determining the dependent variables is derived. Different critical time‐scales are found for tropical relaxation of different dependent variables to be effective. Vorticity has the longest critical time‐scale, typically 1.2 days. For temperature and divergence, the time‐scales are 10 hours and 3 hours, respectively. However not all the tropical fields, in particular the vertical motion, are reproduced correctly by the model unless divergence is heavily damped. To obtain the correct extra‐tropical fields, it is crucial to have the correct rotational flow in the subtropics to initiate the Rossby wave propagation from there. It is sufficient to relax vorticity or temperature on a time‐scale comparable or less than their critical time‐scales to obtain this. However if the divergent advection of vorticity is important in the Rossby Wave Source then strong relaxation of divergence is required to accurately represent the tropical forcing of Rossby waves. Copyright © 2012 Royal Meteorological Society
Laboratory experiments in the system dynamics field
Authors: Arango Aramburo Santiago , Castañeda Acevedo Jaime Andrés , Olaya Morales Yris 
Published: January 2012

AbstractControlled experiments, long used in psychology and economics, are increasingly being used to develop theories in the areas of interest to management science, including decision making and systems. In this paper we review laboratory experiments relating to system dynamics. We discuss how these experiments help to (1) determine causes for subjects' poor performance in dynamic environments and (2) model such behaviour in system dynamics models. Finally, we present the main insights from the works reviewed and propose some ideas for a research agenda. Copyright © 2012 System Dynamics Society
Medical treatment of early‐onset mild gestational hypertension reduces total peripheral vascular resistance and influences maternal and fetal complications
Authors: Vasapollo B. , Novelli G. P. , Gagliardi G. , Tiralongo G. M. , Pisani I. , Manfellotto D. , Giannini L. , Valensise H. 
Published: January 2012

AbstractObjectiveComplications in early‐onset mild gestational hypertension (GH) are better predicted by total peripheral vascular resistance (TPVR) > 1350 dyne than by blood pressure. We therefore aimed to assess the possible reduction of severe complications by lowering TPVR with nitric oxide (NO) donors, oral fluids and standard antihypertensive therapy in women with early‐onset mild GH.MethodsA group of 400 patients with early‐onset (20–27 weeks' gestation) mild GH (systolic and diastolic blood pressure < 170/110 mmHg) and TPVR > 1350 dyne were enrolled in a prospective non‐randomized trial with sequential allocation: 100 patients were treated with nifedipine (Group A); 100 with nifedipine and NO donors (Group B); 100 with nifedipine and oral fluids (Group C); and 100 with nifedipine, NO donors and oral fluids (Group D). TPVR was checked 1 month after initiation of therapy, and the number of patients with severe maternal and fetal complications was recorded in each group. The relationship between reduction in TPVR and the frequency of severe complications was assessed.ResultsSevere complications developed in 51% of patients in Group A, 48% in Group B, 53% in Group C and 35% in Group D, the frequency in Group D being significantly lower than that in the other treatment groups (P < 0.05). A reduction in TPVR of < 15% predicted the occurrence of severe complications with sensitivity 95.2% and specificity 88.3%. In Group D a reduction in TPVR of ≥ 15% was more probable (odds ratio (OR) = 2.03; 95% CI, 1.15–3.60; P < 0.015) and severe complications were less probable (OR = 0.52; 95% CI, 0.29–0.91; P < 0.023).ConclusionIn women with early‐onset mild GH, combined treatment with NO donors, oral fluids and nifedipine optimally reduces TPVR and seems to reduce maternal and fetal complications. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Dissipative effects in the effective field theory of inflation
Authors: Nacir Diana López , Porto Rafael A. , Senatore Leonardo , Zaldarriaga Matias 
Published: January 2012

AbstractWe generalize the effective field theory of single clock inflation to include dissipative effects. Working in unitary gauge we couple a set of composite operators,$$ {\mathcal{O}_{{\mu \nu }}}_{ \ldots } $$, in the effective action which is constrained solely by invariance under time-dependent spatial diffeomorphisms. We restrict ourselves to situations where the degrees of freedom responsible for dissipation do not contribute to the density perturbations at late time. The dynamics of the perturbations is then modified by the appearance of ‘friction’ and noise terms, and assuming certain locality properties for the Green’s functions of these composite operators, we show that there is a regime characterized by a large friction term γ ≫ Hin which the ζ-correlators are dominated by the noise and the power spectrum can be significantly enhanced. We also compute the three point function 〈ζζζ〉 for a wide class of models and discuss under which circumstances large friction leads to an increased level of non-Gaussianities. In particular, under our assumptions, we show that strong dissipation together with the required non-linear realization of the symmetries implies$$ \left| {{f_{\text{NL}}}} \right|\sim \frac{\gamma }{{c_s^2H}} \gg 1 $$. As a paradigmatic example we work out a variation of the ‘trapped inflation’ scenario with local response functions and perform the matching with our effective theory. A detection of the generic type of signatures that result from incorporating dissipative effects during inflation, as we describe here, would teach us about the dynamics of the early universe and also extend the parameter space of inflationary models.
NNLL resummation for squark-antisquark pair production at the LHC
Authors: Beenakker Wim , Brensing Silja , Krämer Michael , Kulesza Anna , Laenen Eric , Niessen Irene 
Published: January 2012

Abstract

We consider the resummation of soft gluon emission for squark-antisquark pair-production at the LHC at next-to-next-to-leading-logarithmic (NNLL) accuracy in the framework of the minimal supersymmetric standard model. We present the analytical ingredients needed for the calculation and provide numerical predictions for the LHC at centre-of-mass energies of 7 and 14 TeV. We find a significant reduction in the scale uncertainty and a considerable increase in the prediction of the total cross section. Compared to the next-to-leading order prediction, the corrections increase the cross section by up to 30% for 1.5 TeV squarks at a centre-of-mass energy of 7 TeV.