Mechanics of the H-Beam Rolling in the Universal Beam Groove

2020 ◽  
Vol 989 ◽  
pp. 622-628
Author(s):  
Danil L. Shvarts ◽  
Sergey O. Nepriakhin
Keyword(s):  
Variational Principle ◽  
Statistical Error ◽  
Geometrical Model ◽  
Total Power ◽  
Forward Slip ◽  
Slip Coefficient ◽  
Load Calculation ◽  
The Mean ◽  
H Beam ◽  
Section Rolling

The formulation and solution of the problem of double-T section rolling in universal groove using the variational principle of minimum total power with aim to determine integral forming and energy-power parameters are presented. Geometrical model of the deformation zone and the kinematically admissible velocity field were constructed accurate within two unknowns: forward slip coefficient ν, flange spread (pulling-down) . The comparison of the calculated values with the experimental data obtained on a laboratory mill 200 confirmed that the variational principle of minimum total power has sufficient accuracy for analysis of double-T section rolling in universal groove. The mean statistical error of torque calculation is 12.3 % while load calculation is 18.7 %.

scholarly journals Demonstrating the Tapered Gridded Estimator (TGE) for the Cosmological HI 21-cm Power Spectrum using 150 MHz GMRT observations

2020 ◽  
Author(s):  
Srijita Pal ◽  
Somnath Bharadwaj ◽  
Abhik Ghosh ◽  
Samir Choudhuri
Keyword(s):  
Power Spectrum ◽  
Unbiased Estimate ◽  
Power Spectra ◽  
Neutral Hydrogen ◽  
Statistical Error ◽  
Temperature Fluctuations ◽  
Radio Frequency Interference ◽  
Rectangular Region ◽  
Angular Power Spectrum ◽  
The Mean

Abstract We apply the Tapered Gridded Estimator (TGE) for estimating the cosmological 21-cm power spectrum from 150 MHz GMRT observations which corresponds to the neutral hydrogen (HI) at redshift z = 8.28. Here TGE is used to measure the Multi-frequency Angular Power Spectrum (MAPS) Cℓ(Δν) first, from which we estimate the 21-cm power spectrum P(k⊥, k∥). The data here are much too small for a detection, and the aim is to demonstrate the capabilities of the estimator. We find that the estimated power spectrum is consistent with the expected foreground and noise behaviour. This demonstrates that this estimator correctly estimates the noise bias and subtracts this out to yield an unbiased estimate of the power spectrum. More than $47\%$ of the frequency channels had to be discarded from the data owing to radio-frequency interference, however the estimated power spectrum does not show any artifacts due to missing channels. Finally, we show that it is possible to suppress the foreground contribution by tapering the sky response at large angular separations from the phase center. We combine the k modes within a rectangular region in the ‘EoR window’ to obtain the spherically binned averaged dimensionless power spectra Δ2(k) along with the statistical error σ associated with the measured Δ2(k). The lowest k-bin yields Δ2(k) = (61.47)2 K2 at k = 1.59 Mpc−1, with σ = (27.40)2 K2. We obtain a 2 σ upper limit of (72.66)2 K2 on the mean squared HI 21-cm brightness temperature fluctuations at k = 1.59 Mpc−1.

scholarly journals О бародиффузии при медленных течениях газовой смеси

2019 ◽  
Vol 89 (5) ◽  
pp. 646
Author(s):  
В.М. Жданов
Keyword(s):  
Equations Of Motion ◽  
Considerable Effect ◽  
Gas Mixture ◽  
Slip Coefficient ◽  
Knudsen Numbers ◽  
Slow Flows ◽  
Diffusion Slip ◽  
The Mean ◽  
The Individual ◽  
Small Knudsen Numbers

AbstractBarodiffusion in slow flows of a gas mixture is studied with an approximation using hydrodynamic equations of motion for the individual mixture components. It is shown that consideration of the viscous momentum transfer and the contribution of Knudsen layers for the mixture flowing in a channel has a considerable effect on the value of the barodiffusion factor. The relations are obtained for the mean diffusion fluxes of components and for the total flux of the mixture in a circular cylindrical capillary; these relations are valid for moderately small Knudsen numbers used for calculation of the diffusion baroeffect and separation effect when the gas mixture flows in a set of capillaries connecting two volumes. The modification of the relations for the barodiffusion factor (and for the diffusion slip coefficient cross-linked with it) allows interpreting the sign alteration of these effects observed experimentally for some gas mixtures at intermediate Knudsen numbers.

Determination of Contact Pressure during Double-T Section Rolling in Universal Beam Groove

2020 ◽  
Vol 299 ◽  
pp. 546-551
Author(s):  
Danil L. Shvarts ◽  
Sergey O. Nepriakhin
Keyword(s):  
Equations Of State ◽  
Rolling Force ◽  
Theoretical Method ◽  
Stress And Strain ◽  
Calculation Error ◽  
State Of Stress ◽  
H Beam ◽  
Section Rolling ◽  
Contact Pressures

Based on application the physical constraint equations of state of stress and strain of the metal for the isotropic medium, we get expressions for components of stress tensor. The new theoretical method for calculation of contact pressures and rolling force during rolling of double-T section in a universal beam groove was developed. Reliability of the method is confirmed by the results of experimental verification for conditions of rolling of H-beam No 35B1, 40K2 and 45B2 from steel 15CrSiNiCu on the universal beam mill of "NTMK". The average calculation error is 6.4%. The new method is recommended for calculation pass design and technological modes of H-beam rolling on rail-beam and section mills, equipped with universal stands.

scholarly journals Autonomic dysfunction: A comparative study of patients with Alzheimer’s and frontotemporal dementia – A pilot study

2017 ◽  
Vol 08 (01) ◽  
pp. 084-088 ◽  
Author(s):  
Thomas Gregor Issac ◽  
Sadanandavalli Retnaswami Chandra ◽  
Neelesh Gupta ◽  
Malligurki Raghurama Rukmani ◽  
S. Deepika ◽  
...  
Keyword(s):  
Frontotemporal Dementia ◽  
Autonomic Dysfunction ◽  
Autonomic Function ◽  
Total Power ◽  
Cardiac Autonomic Function ◽  
The Mean ◽  
Function Testing ◽  
Insight Into ◽  
Diagnostic Importance

ABSTRACT Introduction: In frontotemporal dementia (FTD) and Alzheimer’s disease (AD), central autonomic structures get affected early. An insight into autonomic functions in these patients is likely to be of diagnostic importance and thus help in prognosticating and also probably explain unexplained sudden death in some of these patients. Objectives: The objective of this study is to identify autonomic dysfunction prevailing in patients. Then, if there is dysfunction, is the pattern same or different in these two conditions. And if different it will serve as an additional biomarker for specific diagnosis. Patients and Methods: There were 25 patients and 25 controls and six patients and three controls in AD and FTD groups, respectively. The participants who were recruited were assessed for heart rate variability and conventional cardiac autonomic function testing. The parameters were analyzed using LabChart version 7 software and compared with control population using appropriate statistical methods using SPSS version 22 software. Results: The mean overall total power was low in the FTD group (P < 0.001), and there was significant reduction in the standard deviation of normal-to-normal intervals and root mean square of successive differences (P < 0.001) with elevated sympathovagal balance in the FTD group (P = 0.04). Patients with AD also showed sympathetic dominance, but there was in addition parasympathetic suppression unlike in the FTD group. Conclusion: This study reveals autonomic dysfunction in patients with FTD and AD. Both conditions show sympathetic dominance, probably consecutive to the involvement of central autonomic regulatory structures as a shared domain. It remains to be confirmed if these findings are the cause or effect of neurodegeneration and might open up newer territories of research based on the causal role of neurotransmitters in these regions and thus lead to novel therapeutic options such as yoga. The presence of parasympathetic suppression in AD in addition helps differentiate these two conditions.

A Research on the Forward Slip Coefficient in Alloyed Bar Rolling by the Round-Oval-Round Pass Sequence

2011 ◽  
Vol 413 ◽  
pp. 444-448
Author(s):  
Jian Feng Song ◽  
Yong Gang Dong
Keyword(s):  
Three Dimensional ◽  
Contact Boundary ◽  
Forward Slip ◽  
Slip Coefficient ◽  
Rigid Plastic ◽  
Bar Rolling ◽  
Effective Height ◽  
Rolling Experiment ◽  
Modified Formula ◽  
Round Pass

For predicting the forward slip coefficient and veocity of outgoing workpiece exactly during alloyed bar rolling by Round-Oval-Round pass sequence, the influence of the spred of the outgoing workpiece and its contact boundary condition was considered and the calculating formula for the effective height of outgoing workpiece and the mean roll radius was proposed individually. Moreover, the new parameters were substituted into the Shinokura and Takai Formula to modify it. Then a modified forward slip coefficient firmula was proposed. The validity of the theoretical model has been examined by the bar rolling experiment and the numerical simulation using three-dimensional rigid-plastic FEM. Compared with the Shinokura and Takai dormula, the predict accuracy of the modified formula was improved apparently. So, it can be applied in alloyed bar rolling to predict the the forward slip coefficient and veocity of outgoing workpiece exactly.

Forward Slip and Backward Slip in Radial Ring Rolling Process

2013 ◽  
Vol 423-426 ◽  
pp. 820-823 ◽  
Author(s):  
Yan Liu ◽  
Qiang Wang ◽  
Dong Mei Cai
Keyword(s):  
Rolling Process ◽  
Tangential Component ◽  
Ring Rolling ◽  
Forward Slip ◽  
Slip Coefficient ◽  
Relative Slip ◽  
Speed Difference ◽  
Slip Tendency ◽  
Ring Rolling Process

During the process of radial ring rolling, relative slip or relative slip tendency occurs on the interface between the ring and the rolls. Research on the relative slip or relative slip tendency plays an important role on reducing friction to ensure the ring rolling smoothly. In this paper, the reason of relative slip or relative slip tendency is investigated that there is speed difference between tangential component of the ring and linear velocity of the rolls. According to speed difference, slip types of the interface are classified. Forward slip coefficient and backward slip coefficient are defined and derived and relations between them are studied. Comparison between the new method and the previous one is conducted via case study, which proves the rationality and effectiveness.

Two Methods for Analyzing Waves in Composites with Random Microstructure

1991 ◽  
Vol 253 ◽  
Author(s):  
John R. Willis
Keyword(s):  
Variational Principle ◽  
Variational Principles ◽  
Statistical Information ◽  
Random Microstructure ◽  
Self Consistent ◽  
The Mean ◽  
Stochastic Variational Principles

ABSTRACTThe problem of calculating the mean wave in a composite with random microstructure is addressed. Exact characterizations of the problem can be given, in the form of stochastic variational principles. Substitution of simple configuration-dependent trial fields into these generates approximations which are, in a sense, ‘optimal’. It is necessary in practice to employ only trial fields which will generate, in the variational principle, no more statistical information than is actually available. Trial fields that require knowledge of two-point statistics generate equations that can also be obtained directly, through use of the QCA. The same fields can be substituted into an alternative variational principle to yield an approximation that makes use of three-point statistics – this approximation is less easy to obtain by direct reasoning. When not even two-point information is available, some more elementary approximation is needed. One such approximation, which is simple and direct in its application, is an extension to dynamics of a “self-consistent embedding” scheme which is widely used in static problems. This is also discussed, together with some illustrative results for a matrix containing inclusions and for a polycrystal.

Determination of forward slip in H-beam rolling

1995 ◽  
Vol 54 (1-4) ◽  
pp. 114-119 ◽  
Author(s):  
Wenzhi Zhang ◽  
Chunqing Zhu ◽  
G.E.O. Widera
Keyword(s):  
Forward Slip ◽  
H Beam

scholarly journals Experimental Estimation of Moderator Temperature Coefficient of the IPEN-MB-01 Reactor

2019 ◽  
Vol 7 (2B) ◽  
Author(s):  
Rubens Cavalcante Da Silva
Keyword(s):  
Temperature Coefficient ◽  
Reactor Core ◽  
Mean Value ◽  
Total Power ◽  
Rectangular Array ◽  
Neutron Reflection ◽  
Experimental Estimation ◽  
The Mean ◽  
Using Data ◽  
Coefficient Of Reactivity

The aim of this article is to present the procedure for the experimental estimation of the Moderator Temperature Coefficient of Reactivity of the IPEN/MB-01 Research Reactor, a parameter that has an important role in the physics and the control operations of any reactor facility. At the experiment, the IPEN/MB-01 reactor went critical at the power of 1W (1% of its total power), and whose core configuration was 28x26 rectangular array of UO2 fuel rods, inside a light water (moderator) tank. In addition, there was a heavy water (D2O) reflector installed in the West side of the core to obtain an adequate neutron reflection along the experiment. The moderator temperature was increased in steps of 4oC, and the measurement of the mean moderator temperature was acquired using twelve calibrated thermocouples, placed around the reactor core. As a result, the mean value of -4.81 pcm/°C was obtained for such coefficient. The curves of ρ(T) (Reactivity x Temperature) and  (Moderator Temperature Coefficient of Reactivity x Temperature) were developed using data from an experimental measurement of the integral reactivity curves through the Stable Period and Inverse Kinetics Methods, that was carried out at the reactor with the same core configuration. Such curves were compared and showed a very similar behavior between them.

scholarly journals Modeling and Research of the Deformation Treatment Process of 585 Gold Fineness Alloys for Obtaining Wire for Jewelry Purpose

2021 ◽  
Author(s):  
Sergey Borisovich Sidelnikov ◽  
Yuliia Dmitrievna Ditkovskaia ◽  
Ekaterina Sergeevna Lopatina ◽  
Denis Sergeevich Voroshilov ◽  
Olga Sergeevna Lebedeva ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Treatment Process ◽  
Experimental Studies ◽  
Total Power ◽  
Variation Method ◽  
Section Rolling ◽  
Deformation Treatment ◽  
Palladium Silver

Abstract The results of studies of the process of obtaining wire for the manufacture of jewelry chains from new nickel-free 585 gold fineness alloys are presented.New 585 gold fineness alloys, alloyed with palladium, silver and other elements, and as modifiers - with rhodium and ruthenium in the stated quantities have been proposed.By modeling the process of section rolling of rods in octagonal calibers using the variation method of minimum total power, the broadening of the metal and the energy-power parameters of rolling rods from the investigated alloys have been determined. The regularities of their change have been found. Software has been developed for designing processes for the production of longish deformed semi-finished products and technological modes of rolling and drawing of new gold alloys.With the help of experimental studies, the adequacy of the results of calculations and modeling was checked and new data were obtained on the mechanical properties of the metal and its structure.It has been found that the proposed alloys and the modes of their processing using the processes of section rolling and drawing make it possible in industrial conditions to obtain jewelry wire with a diameter of up to 0.25 mm with the level of mechanical and operational properties required for chain tying.

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